The application of electricity to promote the growth of plants

1348. A profitable application of electricity to promote the growth of plants has not yet been discovered; though it has been a favourite idea with naturalists for more than a century. The following brief account is abridged from a paper on the subject by Professor Solly (published in the Journal of the Horticultural Society of London). The earliest experiments on the subject appear to have been those of Dr. Maimbray of Edinburgh in the year 1746, when he electrified two myrtles during the whole month of October, till at length they put forth fresh branches and flowers. In 1747 a paper was read before the Royal Society on the effects of Electricity on Vegetables, and many experiments were tried in England, France, and Germany on the subject; but they do not appear to have been attended with much success, as we find no experiments of any importance recorded for the next thirty years, though Priestley, Du Hamel, Beccaria, and others, alluded to the subject in their writings, and mentioning the rapid growth which has been observed in plants during a thunder storm, suggested the idea of trying experiments on a large scale. We do not, however, find any important experiments recorded till 1779, about eleven years after Priestley published his History of Electricity. In that year the Count de Lacepede published an account of some experiments which he had tried, from which it appeared that when a plant was electrified, it grew with more vigour than usual, but that the most perceptible effect was produced in forwarding the germination of seeds and the sprouting of bulbs. In 1782, Dr. Marat described several experiments that he had made with electrified seeds, which appear to have been successful; and in France the Abbe Bertholon published a work on the subject (De l'Electricite des Vegetaux), in which he not only details the results of various experiments, but states at great length his opinions on the subject. One of the most curious parts of M. Bertholon's plan was, that he proposed to irrigate the ground in which the plants were to be grown with electrified water, the cistern being lined with resin to insulate the water while it was being electrified. Immediately after the publication of Bertholon's work, several other books were published on the subject in France, Italy, and Germany, but none of the experiments seem to have been attended with success; and an experiment tried by Dr. Gardini in the garden of a monastery at Turin so completely deprived the ground of its fertility, that the monks became exasperated and tore down the wires. Humboldt, in a work on the physiology of plants, published in 1794, observes, that there is scarcely any opinion in which the learned are more divided than that respecting the influence of electricity on vegetation. He evidently himself believes that it has some effect; while De Candolle appears to be of a contrary opinion. Sir Humphry Davy, Du Petit Thouars, Becquerel, and Dutrochet, also tried experiments on the subject, but without producing any marked result. 'In the spring of 1843,' says Professor Solly, 'great interest was excited by the statement which then became current, that a discovery had been made of a means of collecting the natural electricity of the atmosphere so as to increase vegetation in a most extraordinary manner. The statement on which this account was founded originated with Dr. Forster, of Findrassie, Elgin; who, having stretched certain wires in particular directions over a crop of barley, had observed a most luxuriant vegetation produced. About the same time accounts of some American experiments were circulated, from which it appeared that equally extraordinary effects on vegetation had been produced by the influence of feeble currents of voltaic electricity.' (Journ. Hort. Soc., vol. i. p. 99.) In consequence of these statements, experiments were made in various parts of the country, and particularly in the gardens of the Horticultural Society at Chiswick, and in those of the Botanic Society in the Regent's Park; but in all cases the result was a complete failure. In most places the crop was exactly the same as other crops on the same ground without any electricity, and where there was any difference, it was not in favour of the electrical crops. The experiments were discontinued in 1846.